One object, as well as an advantage of the invention, is to utilize a belt conveyor to remove most of the grain stored in a grain bin, and then to use the same conveyor to transmit power to a bin sweep device for removing residual grain from the grain storage bin. Grain storage structures (grain bins) of the type with which the present invention is concerned, include a concrete foundation providing a floor, and on which a series of formed steel rings (i.e. corrugated cylindrical sections) are joined and extend upward to form a cylindrical tank. Many such grain bins have perforated steel floors supported on the concrete foundation and spaced above the floor of the foundation, for purposes of passing air upwardly through the stored grain for aeration of the grain to control the drying and moisture content of the grain and thereby preserve the grain and reduce loss.
Horizontal unloading augers have been principally used in the past to remove the grain from the bin. These augers are placed between or in the concrete foundation and the perforated steel floor, if one is present, or in a trough formed in the foundation; and they extend from the center of the bin through the side wall to several feet outside the bin for discharge into another mass flow auger or conveyor for subsequent transport to market or other use. The unloading auger carries grain away from an enclosed metal frame (well) at the center of the grain bin. The grain flows via gravity into the center well onto the auger. The center well typically has a moveable slide gate which can be operated from outside the grain bin to control grain flow through the well.
Eventually, the bin empties to the point where no additional grain can flow under gravity into the center well, leaving residual grain on the outer edges of the floor of the grain bin extending from the center well and sloping upwards to the outer wall of the bin. The remaining grain, referred to as the residual grain, is considerable, rising from a few inches near the center to as much as ten or twelve feet at the outer wall, for larger diameter bins. The residual grain which, of course, is valuable, is commonly removed from the bin via a powered horizontal sweep auger. This powered horizontal sweep auger rests on the perforated floor and may be placed over the unloading auger prior to filling the grain bin. Commonly, additional intermediate wells are placed over the unloading auger to remove grain from around the powered horizontal sweep auger so it is free of the residual grain pile prior to commencing its rotary “sweep” operation.
The powered horizontal sweep auger is then utilized to move the residual grain from the grain bin by moving the grain toward the center well for transport out of the bin via the unloading auger under the perforated floor. The powered sweep auger is driven mechanically from the central support shaft of the flighted unloading auger and employs a rotating friction wheel on the floor, at its far end, close to the grain bin wall, to continuously drive the sweep auger (which then rotates about the center of the bin) into the residual grain pile. The powered sweep auger rotates angularly, like the hand of a clock, about the center well, delivering the residual grain to the unload auger, until the grain bin is emptied of its contents.
Recent improvements have been made to grain bin unloading systems for purposes of reducing damage to grain. This damage is related to the clearance fit and steel flighting used in conventional unloading auger systems. Belt conveyors fitted under the perforated grain bin floor in place of auger unloading systems are now being employed to minimize damage to high value seed, as well as to improve energy efficiency and reduce unload time.
One limitation to expanding belt conveyor application for unloading grain bins has been the lack of convenient, economical means of driving a horizontal power sweep for removing the residual grain in a grain bin. A belt typically includes a drive roller supported with bearings adjacent a power source, a rubber or plastic material-based belt, and an idler roller supported with bearings at the distal (inboard) end of the belt, in one common form. The belt may be smooth, textured or cleated and ride in a flat or curvilinear support structure. The belt is wrapped around the drive roller and the idler roller, the ends are laced together, the belt is then tensioned by a device at either the drive or idler roller, and the drive roller and belt are driven by an electric or hydraulic motor at the drive roller.
The motor and drive roller are typically located exterior of the bin at or near the discharge of the belt conveyor, whereas the idler roller is located at the center well of the grain bin. The belt conveyor is positioned under the perforated metal grain bin floor and may employ additional intermediate wells for removal of residual grain to clear the region about the power sweep before it is actuated. The drive roller typically employs a bonded rubber coating to provide sufficient traction to transmit power to the conveyor belt.